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      Direct visualization of the dystrophin network on skeletal muscle fiber membrane

      research-article
      The Journal of Cell Biology
      The Rockefeller University Press

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          Abstract

          Dystrophin, the protein product of the Duchenne muscular dystrophy (DMD) gene locus, is expressed on the muscle fiber surface. One key to further understanding of the cellular function of dystrophin would be extended knowledge about its subcellular organization. We have shown that dystrophin molecules are not uniformly distributed over the humen, rat, and mouse skeletal muscle fiber surface using three independent methods. Incubation of single-teased muscle fibers with antibodies to dystrophin revealed a network of denser transversal rings (costameres) and finer longitudinal interconnections. Double staining of longitudinal semithin cryosections for dystrophin and alpha-actinin showed spatial juxtaposition of the costameres to the Z bands. Where peripheral myonuclei precluded direct contact of dystrophin to the Z bands the organization of dystrophin was altered into lacunae harboring the myonucleus. These lacunae were surrounded by a dystrophin ring and covered by a more uniform dystrophin veil. Mechanical skinning of single-teased fibers revealed tighter mechanical connection of dystrophin to the plasma membrane than to the underlying internal domain of the muscle fiber. The entire dystrophin network remained preserved in its structure on isolated muscle sarcolemma and identical in appearance to the pattern observed on teased fibers. Therefore, connection of defined areas of plasma membrane or its constituents such as ion channels to single sarcomeres might be a potential function exerted by dystrophin alone or in conjunction with other submembrane cytoskeletal proteins.

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          Author and article information

          Journal
          J Cell Biol
          J. Cell Biol.
          The Journal of Cell Biology
          The Rockefeller University Press
          0021-9525
          1540-8140
          1 December 1992
          : 119
          : 5
          : 1183-1191
          Article
          93077678
          2289725
          1447296
          939465f6-fec3-436d-b21c-8c1fab8f9da5
          Categories
          Articles

          Cell biology
          Cell biology

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